Center of Gravity Method Equations OPM 533 4- d ix = x coordinate of location i W i = Volume of goods moved to or from location i d iy = y coordinate of location i X Coordinate Y Coordinate
Center-of-Gravity Method Example Quain’s Discount Department Store has four stores located in Chicago, Pittsburg, New York and Atlanta. They are currently being supplied out of an old and inadequate warehouse in Pittsburgh, the site of the chain first store. The firm has decided to find some “central” location in which to build a new warehouse . Data on demand rates and the current location of each store are as above. Number of Containers Store Location Coordinate Shipped per Month Chicago (30, 120) 2,000 Pittsburgh (90, 110) 1,000 New York (130, 130) 1,000 Atlanta (60, 40) 2,000
Center-of-Gravity Method - Example North-South East-West 120 – 90 – 60 – 30 – – | | | | | | 30 60 90 120 150 Arbitrary origin Chicago (30, 120) New York (130, 130) Pittsburgh (90, 110) Atlanta (60, 40)
Center-of-Gravity Method Example Number of Containers Store Location Coordinate Shipped per Month Chicago (30, 120) 2,000 Pittsburgh (90, 110) 1,000 New York (130, 130) 1,000 Atlanta (60, 40) 2,000 x-coordinate = (30)(2000) + (90)(1000) + (130)(1000) + (60)(2000) 2000 + 1000 + 1000 + 2000 = 66.7 y-coordinate = (120)(2000) + (110)(1000) + (130)(1000) + (40)(2000) 2000 + 1000 + 1000 + 2000 = 93.3